#include <bits/stdc++.h>

#define eb emplace_back
#define ep emplace
#define fi first
#define se second
#define in read<int>()
#define lin read<ll>()
#define rep(i, x, y) for(int i = (x); i <= (y); i++)
#define per(i, x, y) for(int i = (x); i >= (y); i--)

using namespace std;

using ll = long long;
using db = double;
using pii = pair < int, int >;
using vec = vector < int >;
using veg = vector < pii >;

template < typename T > T read() {
	T x = 0; bool f = 0; char ch = getchar();
	while(!isdigit(ch)) f |= ch == '-', ch = getchar();
	while(isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar();
	return f ? -x : x;
}

template < typename T > void chkmax(T &x, const T &y) { x = x > y ? x : y; }
template < typename T > void chkmin(T &x, const T &y) { x = x < y ? x : y; }

const int N = 1e6 + 10;
const int T = 1e3 + 10;
const int V = 1e6;

int n;
ll a[N];
int v[N];

int main() {
#ifndef ONLINE_JUDGE
	freopen("1.in", "r", stdin);
#endif
	n = in;
	rep(i, 1, n) {
		a[i] = in; if(v[a[i]]) return printf("%d %d\n", v[a[i]], i), 0;
		v[a[i]] = i;
		
	}
	rep(i, 1, n) {
		rep(k, 2, V) {
			if(a[i] * k >= V) break;
			if(v[a[i] * k]) return printf("%d %d\n", min(v[a[i] * k], i), max(v[a[i] * k], i)), 0;
		}
	}
	puts("-1");
	return 0;
}
